The present invention relates to an electromagnetic actuator and a valve-open-close mechanism used mainly in an automotive internal combustion engine.
Conventional electromagnetic actuators and valve-open-close mechanism are disclosed e.g. in Japanese patent publication 11-93629. Referring to FIG. 1, which shows one embodiment of this invention, an electromagnetic actuator 4 includes a pair of electromagnets 6, 7 each made up of a stator 5 and a coil 18 that are opposed to each other with a gap 10 therebetween. An armature 3 is disposed in the gap 10 so as to be reciprocable between two electrotromagnets 6, 7. A first stem 15 for transmitting the movement of the armature 3 from the other electromagnet 6 toward the one electromagnet 7 to a valve 9 for opening and closing a valve of an internal combustion engine is provided on one surface of the armature, namely, at the side where there is the electromagnet 7.
With this electromagnetic actuator, since the armature 3 is moved between the two electromagnets 6 and 7, it has to be made from a ferromagnetic material. Thus, for the armature 3, an iron-family or a steel-family magnetic material is ordinarily used. Since the first stem 15 is usually integral with the armature 3, an iron-family or steel-family material is used for the first stem 15, too.
Thus, because an iron-family or steel-family heavy material is used for both the armature 3 and the first stem 15, they have an influence on the driving power consumption of the electromagnetic actuator as inertia weight during operation. Thus, if such an electromagnetic actuator is used in an automobile, it will have a direct influence on the fuel consumption.
An object of the present invention is to reduce the weight of an electromagnetic actuator and a valve-open-close mechanism used in an internal combustion engine by forming its stems from a lighter material than conventional.
According to this invention, by forming the first stem 15 from a lighter material than conventional, it is possible to reduce the total weight of the combination of the armature 3 and the first stem 15, reduce the driving power consumption for the electromagnetic actuator as the inertia weight during operation, and reduce the fuel consumption if this is used in an automobile.
That is to say, a pair of electromagnets 6, 7 formed of stators 5 and coils 18 are opposed to each other with a gap 10 therebetween; an armature 3 is disposed in the gap 10 so that the armature 3 is reciprocable between one electromagnet 7 and the other electromagnet 6 by driving the electromagnets 6 and 7; a first stem 15 for transmitting the movement of the armature 3 from the other electromagnet 6 toward the one electromagnet 7 to a valve 9 of an internal combustion engine is inserted in a guide hole 22 formed in the stator 5 of the electromagnet 7; and the first stem 15 is formed of a lighter material than the armature 3.
Also, the electromagnetic actuator as described above is housed in a housing 8 which is mounted to an internal combustion engine body 19 by fixing members; a valve 9 for communicating an intake port 25 or an exhaust port 26 of the internal combustion engine with a combustion chamber 27 or shutting them off from each other is provided in the internal combustion engine body 19; the tip of the first stem 15 of the electromagnetic actuator is brought into abutment with the tip of the valve 9 so that by moving the armature 3 from the electromagnet 6 toward the electromagnet 7, the first stem 15 opens the valve 9 by pushing it; in order to impart a biasing force for carrying out a valve-closing operation to the valve, a retainer 13 is provided on the valve 9, and a first return spring 2 is mounted between the retainer 13 and the internal combustion engine body 19; by inserting a second stem 14 in a guide hole 22 provided in the stator 5 of the other electromagnet 6, it is detachably brought into contact with a surface of the armature 3 on the side not coupled to the first stem 15; and a retainer 13xe2x80x2 is provided on the second stem 14, and a second return spring 1 for imparting a biasing force in the direction in which the second stem 14 pushes the armature 3 is mounted between the retainer 13xe2x80x2 and the housing 8.
Since a light material compared with an iron-family or a steel-family member, which has a specific weight of 7 to 8, is used as the first stem 15, it is possible to reduce the total weight of an electromagnetic actuator for an internal combustion engine and an electronic valve-open-close mechanism for an internal combustion engine, and reduce the driving power consumption for the electromagnetic actuator as the inertial weight during operation.
Also, by coupling the armature 3 and the first stem 15 by slidable coupling, joining or mecahnical fastening, as in the case in which the stem and the armature are of iron or steel material and they are integral, the first stem 15 can transmit the movement of the armature 3 to the valve 9 of the internal combustion engine.